341 research outputs found
A needle in the haystack – the dire straits of needle exchange in Hungary
Abstract Background The two largest needle exchange programs (NEPs) in Hungary were forced to close down in the second half of 2014 due to extreme political attacks and related lack of government funding. The closures occurred against a background of rapid expansion in Hungary of injectable new psychoactive substances, which are associated with very frequent injecting episodes and syringe sharing. The aim of our analysis was to predict how the overall Hungarian NEP syringe supply was affected by the closures. Methods We analyzed all registry data from all NEPs in Hungary for all years of standardized NEP data collection protocols currently in use (2008–2014) concerning 22 949 client enrollments, 9 211 new clients, 228 167 client contacts, 3 160 560 distributed syringes, and 2 077 676 collected syringes. Results We found that while the combined share of the two now closed NEPs decreased over time, even in their partial year 2014 they still distributed and collected about half of all syringes, and attended to over half of all clients and client contacts in Hungary. The number of distributed syringes per PWID (WHO minimum target = 100) was 81 in 2014 in Hungary, but 39 without the two now closed NEPs. Conclusions There is a high probability that the combination of decreased NEP coverage and the increased injection risk of new psychoactive substances may lead in Hungary to a public health disaster similar to the HIV outbreaks in Romania and Greece. This can be avoided only by an immediate change in the attitude of the Hungarian government towards harm reduction
Topological Strata of Weighted Complex Networks
The statistical mechanical approach to complex networks is the dominant
paradigm in describing natural and societal complex systems. The study of
network properties, and their implications on dynamical processes, mostly focus
on locally defined quantities of nodes and edges, such as node degrees, edge
weights and --more recently-- correlations between neighboring nodes. However,
statistical methods quickly become cumbersome when dealing with many-body
properties and do not capture the precise mesoscopic structure of complex
networks. Here we introduce a novel method, based on persistent homology, to
detect particular non-local structures, akin to weighted holes within the
link-weight network fabric, which are invisible to existing methods. Their
properties divide weighted networks in two broad classes: one is characterized
by small hierarchically nested holes, while the second displays larger and
longer living inhomogeneities. These classes cannot be reduced to known local
or quasilocal network properties, because of the intrinsic non-locality of
homological properties, and thus yield a new classification built on high order
coordination patterns. Our results show that topology can provide novel
insights relevant for many-body interactions in social and spatial networks.
Moreover, this new method creates the first bridge between network theory and
algebraic topology, which will allow to import the toolset of algebraic methods
to complex systems.Comment: 26 pages, 19 figures, 1 tabl
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
Living on the edge: utilising lidar data to assess the importance of vegetation structure for avian diversity in fragmented woodlands and their edges
Context: In agricultural landscapes, small woodland patches can be important wildlife refuges. Their value in maintaining biodiversity may, however, be compromised by isolation, and so knowledge about the role of habitat structure is vital to understand the drivers of diversity. This study examined how avian diversity and abundance were related to habitat structure in four small woods in an agricultural landscape in eastern England. Objectives: The aims were to examine the edge effect on bird diversity and abundance, and the contributory role of vegetation structure. Specifically: what is the role of vegetation structure on edge effects, and which edge structures support the greatest bird diversity? Methods: Annual breeding bird census data for 28 species were combined with airborne lidar data in linear mixed models fitted separately at (i) the whole wood level, and (ii) for the woodland edges only. Results: Despite relatively small woodland areas (4.9–9.4 ha), bird diversity increased significantly towards the edges, being driven in part by vegetation structure. At the whole woods level, diversity was positively associated with increased vegetation above 0.5 m and especially with increasing vegetation density in the understorey layer, which was more abundant at the woodland edges. Diversity along the edges was largely driven by the density of vegetation below 4 m. Conclusions: The results demonstrate that bird diversity was maximised by a diverse vegetation structure across the wood and especially a dense understorey along the edge. These findings can assist bird conservation by guiding habitat management of remaining woodland patches
Genetic variation and exercise-induced muscle damage: implications for athletic performance, injury and ageing.
Prolonged unaccustomed exercise involving muscle lengthening (eccentric) actions can result in ultrastructural muscle disruption, impaired excitation-contraction coupling, inflammation and muscle protein degradation. This process is associated with delayed onset muscle soreness and is referred to as exercise-induced muscle damage. Although a certain amount of muscle damage may be necessary for adaptation to occur, excessive damage or inadequate recovery from exercise-induced muscle damage can increase injury risk, particularly in older individuals, who experience more damage and require longer to recover from muscle damaging exercise than younger adults. Furthermore, it is apparent that inter-individual variation exists in the response to exercise-induced muscle damage, and there is evidence that genetic variability may play a key role. Although this area of research is in its infancy, certain gene variations, or polymorphisms have been associated with exercise-induced muscle damage (i.e. individuals with certain genotypes experience greater muscle damage, and require longer recovery, following strenuous exercise). These polymorphisms include ACTN3 (R577X, rs1815739), TNF (-308 G>A, rs1800629), IL6 (-174 G>C, rs1800795), and IGF2 (ApaI, 17200 G>A, rs680). Knowing how someone is likely to respond to a particular type of exercise could help coaches/practitioners individualise the exercise training of their athletes/patients, thus maximising recovery and adaptation, while reducing overload-associated injury risk. The purpose of this review is to provide a critical analysis of the literature concerning gene polymorphisms associated with exercise-induced muscle damage, both in young and older individuals, and to highlight the potential mechanisms underpinning these associations, thus providing a better understanding of exercise-induced muscle damage
Urban Biodiversity and Landscape Ecology: Patterns, Processes and Planning
Effective planning for biodiversity in cities and towns is increasingly important as urban areas and their human populations grow, both to achieve conservation goals and because ecological communities support services on which humans depend. Landscape ecology provides important frameworks for understanding and conserving urban biodiversity both within cities and considering whole cities in their regional context, and has played an important role in the development of a substantial and expanding body of knowledge about urban landscapes and communities. Characteristics of the whole city including size, overall amount of green space, age and regional context are important considerations for understanding and planning for biotic assemblages at the scale of entire cities, but have received relatively little research attention. Studies of biodiversity within cities are more abundant and show that longstanding principles regarding how patch size, configuration and composition influence biodiversity apply to urban areas as they do in other habitats. However, the fine spatial scales at which urban areas are fragmented and the altered temporal dynamics compared to non-urban areas indicate a need to apply hierarchical multi-scalar landscape ecology models to urban environments. Transferring results from landscape-scale urban biodiversity research into planning remains challenging, not least because of the requirements for urban green space to provide multiple functions. An increasing array of tools is available to meet this challenge and increasingly requires ecologists to work with planners to address biodiversity challenges. Biodiversity conservation and enhancement is just one strand in urban planning, but is increasingly important in a rapidly urbanising world
Ecological distribution and population physiology defined by proteomics in a natural microbial community
Community proteomics applied to natural microbial biofilms resolves how the physiology of different populations from a model ecosystem change with measured environmental factors in situ.The initial colonists, Leptospirillum Group II bacteria, persist throughout ecological succession and dominate all communities, a pattern that resembles community assembly patterns in some macroecological systems.Interspecies interactions, and not abiotic environmental factors, demonstrate the strongest correlation to physiological changes of Leptospirillum Group II.Environmental niches of subdominant populations seem to be determined by combinations of specific sets of abiotic environmental factors
Increasing prevalence of HIV infection among first time clients in Italian drug treatment services – is it sexual transmission?
A Review of One-Way and Two-Way Experiments to Test the Isotropy of the Speed of Light
As we approach the 125th anniversary of the Michelson-Morley experiment in
2012, we review experiments that test the isotropy of the speed of light.
Previous measurements are categorized into one-way (single-trip) and two-way
(round-trip averaged or over closed paths) approaches and the level of
experimental verification that these experiments provide is discussed. The
isotropy of the speed of light is one of the postulates of the Special Theory
of Relativity (STR) and, consequently, this phenomenon has been subject to
considerable experimental scrutiny. Here, we tabulate significant experiments
performed since 1881 and attempt to indicate a direction for future
investigation.Comment: Updated Fig. 7 and references; Revised sections 3.2 and 4. Accepted
in the Indian Journal of Physics on March 30, 201
Influence of substrate on the richness and composition of Neotropical cave fauna
ABSTRACT The food base in the subterranean environment consists mainly of allochthonous materials. In this environment the resources are distributed generally in a heterogeneous dispersed way and the distribution of resources and their availability determine where the terrestrial invertebrates will reside, which is important for understanding ecological relationships and to establish conservation strategies. Thus, we tested how the complexity of substrates influences the richness and composition of the subterranean terrestrial invertebrates in the Presidente Olegário karst area, southeastern Brazil. We carried out collections in six caves during both dry and wet seasons, using combined collection methods. We observed different distributions in relation to the substrate, because the environmental heterogeneity increases the amount of available niches for the fauna. Some taxa showed a preference for specific substrates, probably related to the availability of food resources and humidity and to body size restriction, emphasizing the niche differentiation between species. Anthropogenic impacts can cause irreversible alterations in the subterranean fauna because the subterranean environment is dependent on the surface for input of trophic resources. On-going impacts in the Presidente Olegario karst area, like agriculture, pastures, gas extraction, and hydroelectric projects, are therefore a serious threat to subterranean biodiversity and this region should be prioritized for conservation
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